Aircraft and other vehicles typically include external surfaces formed from panels, sheets, or plates. Because the panels alone are typically too weak to withstand operational loads, they are strengthened by adding honeycomb cores (e.g., between two composite sheets) and/or other stiffeners or supports. For example, aluminum panels can be strengthened with aluminum supports, and composite panels (which may be lighter weight) are typically strengthened with composite supports. FIG. 1 is a partially schematic, isometric view of a composite structure 1 that includes a composite sheet 2 strengthened by composite supports 3, in accordance with the prior art. One drawback with this arrangement is that the composite supports 3 can be expensive to produce. Additionally, it is sometimes difficult to tailor the characteristics of the composite structure 1 to meet the structural requirements of a particular design.